%0 Journal Article %A Rainu Bawa %A Stephen Perrio %A Vineet Prakash %A Paul Murray %T Is a negative CTPA good enough to exclude pulmonary embolism? %D 2014 %J European Respiratory Journal %P P674 %V 44 %N Suppl 58 %X Introduction:National guidelines exist for the investigation of pulmonary embolism (PE). CTPA is the gold standard investigation. Clinical probability should be determined pre-CTPA by using the Wells score and d-dimer testing. Diagnostic yield of CTPA for PE is low (18 -36%). Is a negative CTPA always good enough to safely exclude a PE in everyday clinical practice?Method:We conducted a cross-sectional retrospective study on 100 consecutive CTPAs performed within our hospital group looking for PEs from 2013. From these scans, 25 case notes were reviewed (5 +ve PEs, 20 -ve PEs) to correlate request form and findings with recorded Wells score, d-dimer results and possible alternative diagnoses. The opacification of the main PA must be >250 HUs to be considered adequate for scanning and should be achieved in at least 90% of scans.Results:Of the 100 CTPAs, 98 were included in the study. 56 scans (57.1%) had adequate opacification (mean 272 HUs, range 76 - 533 HUs). 18 scans confirmed PE (18.4%). 13 (72%) of these had adequate opacification. Of the 80 (81.6%) negative scans only 43 (54%) had adequate opacification. The 20 -ve PE case notes reviewed showed 13 (65%) had a Wells score and d-dimer recorded.Conclusion:The review of 20 -ve PE cases revealed that 10 (50%) had inadequate PA opacification. Of these 7 (35%) could be stratified as either high risk (Wells >4, or +ve d-dimer) or having insufficient clinical data and so questioning the need for additional investigation to exclude PE as the -ve CTPA was not conclusive. Our data suggests that a large number of -ve CTPAs are inadequate in excluding PEs in high risk or poorly risk stratified patients and must not be the final investigation when concern for PE remains high. %U